As a sophomore, Ptacek started two games at the left halfback position for the 1956 Michigan Wolverines football team.[3] He completed 15 of 23 passes for 245 yards, two interceptions and three touchdowns. He also rushed for 208 yards on 45 carries and caught seven passes for 53 yards.[4]

As a junior in 1957, Ptacek did not start any games,[5] completed two of three passes, gained 186 rushing yards on 60 carries, and caught eight passes for 88 yards.[4]

As a senior, Ptacek started all nine games at quarterback for the 1958 Michigan Wolverines football team that compiled a 2-6-1 record.[6] He played on both offense and defense in 1958, remaining on the field for 51 of 60 minutes in a 20-19 victory over Minnesota; an Associated Press story referred to him as one of football's "vanishing breed -- the iron man."[7] He was selected as the Most Valuable Player on the 1958 team,[6] completing 65 of 115 passes for 760 yards, nine interceptions and three touchdowns.[4] In the 1958 Michigan-Ohio State game, Ptacek set a Big Ten Conference record of 24 pass completions in a single game; Ptacek's 24 completions were good for 241 yards and two touchdowns.[8]

After the conclusion of the 1958 season, Ptacek was selected to play at the quarterback position for the college all-star teams in both the Hula Bowl and the College All-Star Game. He completed 12 of 26 passes for 136 yards and two touchdowns and rushed for 152 yards, including a 43-yard touchdown run, against the NFL all-stars in the January 1959 Hula Bowl.[9] He was named the Most Valuable Player in the August 1959 College All-Star game after completing five of eight passes against the NFL champion Baltimore Colts.[10]

In an unusual NFL-CFL transaction, the Browns in May 1960 dealt Ptacek to the Saskatchewan Roughriders of the Canadian Football League (CFL) in exchange for Jim Marshall.[11] Ptacek played for Saskatchewan from 1960 to 1965. He had his career-best season in 1962, completing 125 of 206 passes for 2,317 yards, 15 touchdowns and 10 interceptions. During his six-year CFL career, Ptacek scored four rushingtouchdowns on offense and two on interception returns. He completed 299 of 525 passes for 25 touchdowns.[12] He was named to the All-Canadian team as a defensive back in 1964 as well as All-WFC in 1961 as a linebacker and 1964 defensive back.[12] He was inducted into the Saskatchewan Roughriders Plaza of Honour in 2001.[13]

He holds the CFL record for most fumble returns in a playoff season with three in 1963.[14]